1. Field of the Invention
The present invention relates generally to initial data transmission and data retransmission in a CDMA (Code Division Multiple Access) mobile communication system, and in particular, to a method of initial data transmission and data retransmission to ensure high data rate for the provisioning of multimedia service in a mobile communication system.
2. Description of the Related Art
1× EV-DO (Evolution-Data Only) is a high data rate transmission system based on the Qualcomm's HDR (High Data Rate) technology. This mobile communication system transmits data blocks in time division at a predetermined data rate. The data blocks are channel-encoded to minimize errors that may be generated during transmission on a radio channel and transmitted by HARQ (Hybrid Automatic ReQuest) to maximize reception performance. Although the length of a data block is determined according to the data rate, if an initially transmitted data block has errors, a data block of the same size should be retransmitted so that a receiver can recover the defective data block by combining and decoding. In 1× EV-DO and 1× EV-DV (Evolution-Data and Voice), data block sizes depend on data rates. Therefore if an initially transmitted data block has errors and a given data rate for retransmission does not support the size of the initially transmitted data block, a transmitter should retransmit a long data block at a low data rate determined as downing or a data block at a high data rate determined as increasing. Such retransmission method results in an increased error probability, namely retransmission probability, and large radio resource consumption, thereby deteriorating the system performance.